Stacked Ceramic Patch Antennas With Patterned Cavities for Dual-Band Bandwidth
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Solution Overview
Problem
Conventional ceramic substrate-based patch antennas face challenges in achieving dual-band operation with sufficient bandwidth due to the inverse proportionality of the quality factor (Q) and volume, leading to size disparities and limited bandwidth.
Innovation Solution
A stacked patch antenna design utilizing a molded ceramic puck with perforated air-cavities as the substrate, where the effective permittivity is reduced by introducing voids, allowing for increased L1-band resonance volume without significant weight change, thereby widening the bandwidth and enabling flexible size adjustments through cavity positioning and pattern manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If ceramic substrate is used to reduce antenna size, then the antenna size is reduced, but the bandwidth is narrowed
Solution Approach 1:
The patent introduces air cavities (porous structure) into the ceramic substrate, creating a patterned configuration of ceramic material and air regions. This porous structure reduces the effective permittivity of the substrate while maintaining mechanical support, thereby increasing the bandwidth without significantly increasing the antenna volume. The air cavities create regions of lower effective dielectric constant, which broadens the resonant bandwidth according to the Chu-Harrington limit.
Solution Approach 2:
The substrate is designed as a composite structure combining ceramic material and air cavities in a patterned arrangement. This composite approach allows optimization of both mechanical properties (from ceramic) and electromagnetic properties (from the ceramic-air composite with lower effective permittivity), resolving the contradiction between size reduction and bandwidth maintenance.
2Volume of moving object
If high DK ceramic material is used to reduce antenna size, then the antenna size is reduced, but the quality factor Q increases which narrows bandwidth
Solution Approach 1:
By introducing air cavities into the high DK ceramic substrate, the effective permittivity is reduced while maintaining the compact size enabled by the high DK material. The porous structure creates a balance where the antenna remains electrically small (maintaining high Q for size reduction) but the effective permittivity is lowered to broaden the bandwidth, thus managing the quality factor to achieve both size reduction and acceptable bandwidth.
3Adaptability or versatility
If stacked patches are used to cover dual-band requirements, then frequency coverage is improved, but the size disparity between patches increases
Solution Approach 1:
The patent applies different properties to different regions of the substrate by creating patterned air cavities in specific locations. This local modification of the substrate permittivity allows optimization of each patch's resonant frequency and size independently, reducing the size disparity between stacked patches while maintaining dual-band frequency coverage. The cavity patterns can be tailored to compensate for the natural size differences between L1 and L2 band patches.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the bandwidth and reduces the antenna's overall weight, allowing for improved size flexibility and control over frequency ratios between modes, effectively addressing the limitations of conventional ceramic substrates.
Implementation Method 1
The effective permittivity in the perforated dielectric region is determined from the porosity, or void fraction of the perforation, defined as the fraction of the volume of the voids-space over the total bulk volume of the material.
Implementation Method 2
only one set of direct feeds to the top patch radiator is applied since the excitation of the bottom patch (L2 band) element is through parasitic coupling.
Implementation Method 3
For circular patches, the fundamental mode of operation is TM11 mode, which has an upper-hemisphere radiation pattern that works well for GNSS applications.
Data Source
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AI summary
A GNSS RHCP stacked patch antenna with wide dual band, high efficiency and small size is made of a molded high-permittivity material, such as ceramics, with a patterned cavity in the dielectric substrate. The perforated cavities in the substrate reduce the effective dielectric constant, increase the bandwidth and efficiency. The high-order modes can be manipulated through the design of cavities.